Pivot thrust reverser surrounding inner surface of bypass duct

ABSTRACT

A pivot thrust reverser includes a first pivot door forming a first portion of a nacelle when stowed and second pivot door forming a second portion of the nacelle when stowed. The first pivot door and second pivot door each form a portion of a surface of a bypass duct when in a stowed position. In the deployed position the first pivot door and the second pivot door circumferentially surround a portion of an inner surface of a bypass duct such that when the pivot thrust reverser is deployed during engine operation a fan bypass stream is redirected while both a core stream and a nacelle ventilation stream flow in substantially the same manner as when the pivot thrust reverser is stowed.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/768,154, entitled “ATR PIVOT THRUST REVERSER WITH CONTOURING AROUND CORE,” filed Feb. 22, 2013, which is hereby incorporated by reference in its entirety. Priority is also claimed to U.S. Provisional Patent Applications Ser. Nos. 61/768,160, entitled “ATR TANDEM THRUST REVERSER,” filed Feb. 22, 2013; 61/768,166, entitled “ATR TANDEM THRUST REVERSER WITH 4-BAR LINKAGE,” filed Feb. 22, 2013; 61/768,171, entitled “ATR CONTOURED THRUST REVERSER WITH 3 POINT ACUATION,” filed Feb. 22, 2013; and 61/768,172, entitled “AIR TANDEM THRUST REVERSER WITH 3 POINT ACTUATION,” filed Feb. 22, 2013. All of these are hereby incorporated by reference in their entirety.

BACKGROUND

The presently disclosed embodiments relate generally to gas turbine engine and/or nacelle assemblies and, more particularly, to thrust reversers used in gas turbine engine and/or nacelle assemblies.

Thrust reversers in gas turbine engine and/or nacelle assemblies are deployed to redirect an aircraft's propulsive air flow, such as in a forward direction rather than aft. This can provide deceleration for the aircraft which, for example, can assist in slowing the aircraft down during landing, and therefore, enable shorter landing distances while reducing stress and wear on an aircraft's brakes. Thrust reversers are particularly useful when a landing surface is icy or wet, and consequently, the aircraft's brakes are less effective.

Commercial gas turbine engines typically include an engine which produces high temperature, high pressure exhaust ejected through a nozzle downstream of the engine, and a bypass duct, which is generally an annular space concentrically located about the engine through which air from the engine fan, known as the fan bypass stream, is passed. Many aircraft applications use high bypass ratio gas turbine engines, where a majority of the aircraft's propulsion is provided by the fan bypass stream, rather than by the exhaust produced from the engine. In such applications, a thrust reverser may be able to operate effectively by redirecting the fan bypass stream alone.

However, providing a thrust reverser to redirect the fan bypass stream presents design challenges. The thrust reverser must be part of an overall aerodynamic design when stowed, yet be capable of effectively deploying at an appropriate angle which captures enough of the fan bypass stream, and redirects this fan bypass stream at the needed angle, to provide deceleration. To obtain thrust reverser designs which accomplish this, complex assemblies with a multitude of parts have generally been used, often requiring translating parts relative to the engine to allow the thrust reverser to deploy at an effective location. These designs also have generally included an obstruction present in the fan bypass stream reversal flow path, such as actuators or linkages. Moreover, these complex designs are less reliable and require greater maintenance costs. Even with these complex designs, significant portions of the fan bypass stream are not redirected, resulting in a less efficient thrust reverser and, as a consequence, the need for longer landing distances and increased wear on the aircraft's brakes.

SUMMARY

One embodiment of the present invention includes a pivot thrust reverser for use in a gas turbine engine assembly. The thrust reverser includes a first pivot door forming a first portion of a nacelle when stowed, and a second pivot door spaced from the first pivot door forming a second portion of the nacelle when stowed. The first pivot door and the second pivot door each form a portion of a surface of a bypass duct when in a stowed position. In the deployed position the first pivot door and the second pivot door circumferentially surround a portion of an inner surface of a bypass duct such that when the pivot thrust reverser is deployed during engine operation a fan bypass stream is redirected while both a core stream and a nacelle ventilation stream flow substantially in the same manner as when the pivot thrust reverser is stowed.

Another embodiment includes a method for reversing thrust of a gas turbine engine assembly. A first pivot door is provided. The first pivot door forms both a portion of a surface of a bypass duct and a portion of an outer surface of a nacelle when in a stowed position. A second pivot door spaced from the first pivot door is provided. The second pivot door forms both a portion of the surface of the bypass duct and a portion of the outer surface of the nacelle when in the stowed position. Both the first pivot door and the second pivot door are pivotally deployed from the stowed position to a deployed position by an actuator. The actuator is located between the surface of the bypass duct and the outer surface of the nacelle. The first pivot door and the second pivot door together circumferentially surround a portion of an inner surface of a bypass duct when the first pivot door and the second pivot door are in the deployed position. A fan bypass stream is redirected during engine operation when the first pivot door and the second pivot door are in the deployed position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an embodiment of a gas turbine engine and nacelle assembly with a thrust reverser according to the present invention, shown in a stowed position.

FIG. 1B is a perspective view of the gas turbine engine and nacelle assembly of FIG. 1A with the thrust reverser shown in a deployed position.

FIG. 2 is a sectional view of an aft end of the gas turbine engine of FIG. 1B, taken along line 2-2 of FIG. 1B.

FIG. 3 is a perspective view of a pivot door of the thrust reverser and a portion of a bypass duct surface.

FIG. 4 is an aft elevation view of the gas turbine engine shown with the thrust reverser in a deployed position and interior structures of the engine omitted.

FIG. 5 is a perspective view of the thrust reverser with a single actuator in a deployed position.

While the above-identified drawing figures set forth at least one embodiment of the invention, other embodiments are also contemplated. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings.

DETAILED DESCRIPTION

Generally, a pivot thrust reverser can be deployed to surround (or, synonymously, contour around) a portion of a gas turbine engine inner bypass duct wall such that a fan bypass stream is interrupted and reversed with relatively little leakage, while a core stream and a nacelle ventilation stream are unobstructed or substantially unobstructed. When stowed, thrust reverser pivot doors can make up a portion of both a surface of a bypass duct (e.g., an outer duct wall) and an outer surface of a nacelle. The pivot doors can be pivotally deployed from a stowed position to a deployed position by a single actuator on pivot axises that are positionally fixed relative to the gas turbine engine.

FIGS. 1A, 1B, and 2 show an embodiment of gas turbine engine and nacelle assembly 10. FIG 1A shows a perspective view of assembly 10 with pivot thrust reverser 20 in the stowed position. FIG. 1B shows a perspective view of assembly 10 with pivot thrust reverser 20 in a deployed position. FIG. 2 shows a partial sectional view of an aft end of assembly 10, taken along line 2-2 of FIG. 1B and reveals a portion of the interior of engine 18. Assembly 10 includes nacelle 12, outer surface 14 of nacelle 12, projection 15 of nacelle 12, pylon 16, engine 18, nacelle opening 19, pivot thrust reverser 20 with first pivot door 22 and second pivot door 24, low pressure spool 21, high pressure spool 23, combustor 25, bypass duct 26, high pressure turbine 27, outer surface 28 of bypass duct 26, low pressure turbine 29, inner surface 30 of bypass duct 26, axis A of assembly 10, fan bypass stream F₁, redirected fan bypass stream F_(1′), nacelle ventilation stream F₂, and core stream F₃. Certain components of assembly 10, such as a fan, have been omitted for simplicity. Nacelle 12 provides an annular housing within which a substantial portion of engine 18 is located. Engine 18 is aligned on axis A of assembly 10 in the illustrated embodiment. Engine 18 includes combustor 25, high pressure turbine 27, low pressure turbine 29, low pressure spool 21 which connects low pressure turbine 29 to the fan, and high pressure spool 23 which connects high pressure turbine 27 to a compressor. In combination these components, among others, produce hot combustion gases that provide operational energy for engine 18. Pylon 16 provides a means for mounting assembly 10 to an aircraft (not shown). Pivot thrust reverser 20 includes both first pivot door 22 and second pivot door 24. As shown here, second pivot door 24 is spaced approximately 180° from first pivot door 22 relative to axis A of assembly 10.

When stowed, as shown in FIG. 1A, first pivot door 22 and second pivot door 24 each form a portion of outer surface 14, such that outer surface 14 is substantially smooth at all points along an exterior of nacelle 12, including interfaces with first pivot door 22 and second pivot door 24. Because first pivot door 22 and second pivot door 24 provide a smooth outer surface 14 of nacelle 12, pivot thrust reverser 20 tends to reduce a risk of undesired aerodynamic concerns.

Inner surface 30 of bypass duct 26 provides an outer surface of a wall covering engine 18. Bypass duct 26 is defined by the annular space within nacelle 12 between inner surface 30 and outer surface 28 of bypass duct 26. A portion of outer surface 28 of bypass duct 26 is formed by the interior of nacelle 12 with the other portion of outer surface 28 of bypass duct 26, where opening 19 is located, formed by first pivot door 22 and second pivot door 24 when in the stowed position, as shown in FIG. 1A.

Both first pivot door 22 and second pivot door 24 can pivot on respective pivot axises that are each positionally fixed relative to assembly 10. Thus, first pivot door 22 and second pivot door 24 only pivot into the deployed position, without requiring any translation of portions of nacelle 12, first pivot door 22, or second pivot door 24 of assembly 10. Both first pivot door 22 and second pivot door 24 pivot into opening 19 so as to open upstream from an aft end of nacelle 12, such that first pivot door 22 and second pivot door 24 pivot open inside of nacelle 12, obstructing the flow through bypass duct 26.

Fan bypass stream F₁ is relatively cold air which enters through the fan at the front end of nacelle 12 and passes through bypass duct 26. When pivot thrust reverser 20 is in the stowed position, fan bypass stream F₁ exits from an aft end of nacelle 12 and provides a majority of the propulsion generated by the high bypass gas turbine engine. However, when pivot thrust reverser 20 is in the deployed position, as shown in FIGS. 1B and 2, first pivot door 22 and second pivot door 24 open inside of nacelle 12 and obstruct at least a portion of the flow of fan bypass stream F₁ through bypass duct 26, such that a redirected fan bypass stream F_(1′) no longer exits from the aft end of nacelle 12, but is instead diverted in another direction. Redirected fan bypass stream F_(1′) is redirected by deployed pivot thrust reverser 20 to flow in the forward, or upstream, direction shown here. Importantly, pivot thrust reverser 20 is configured such that there need not be any actuators, linkages, or other obstructions present in F_(1′) flow path when pivot thrust reverser 20 is in the deployed position, which could otherwise obstruct the flow of fan bypass stream F_(1′) in the forward direction, thus reducing the effectiveness of pivot thrust reverser 20. Redirecting fan bypass stream F_(1′) as shown can not only prevent fan bypass stream F_(1′) from providing forward propulsion, but can also actively provide deceleration. Yet, nacelle ventilation stream F₂ and core stream F₃, which flow through the inside of engine 18, can remain unobstructed and continue to flow out downstream of engine 18 when pivot thrust reverser 20 is deployed in substantially the same manner as when pivot thrust reverser 20 is in the stowed position.

FIG. 3 is a perspective view of second pivot door 24 of pivot thrust reverser 20. In addition to a portion of outer surface 28 of bypass duct 26, also shown are edge curvature 36 and rotational curvature R. For pivot thrust reverser 20 to be effective, the pivot doors, including second pivot door 24, must be able to pivot and open at an appropriate angle into the deployed position without being obstructed by projection 15 of nacelle 12. If the pivot doors are obstructed from opening at the appropriate angle by projection 15 of nacelle 12, fan bypass stream F₁ will not be redirected in the forward direction. To avoid this obstruction, the pivot axis for second pivot door 24 must be placed at a location on nacelle 12 that allows second pivot door 24 to pivot along rotational curvature R. Furthermore, second pivot door 24 can have edge curvature 36 to allow second pivot door 24 to tightly surround inner surface 30 of bypass duct 26, as will be discussed below.

FIG. 4 is an aft elevation view of assembly 10 shown with pivot thrust reverser 20 in the deployed position, and certain interior structures of engine 18 (e.g., turbine blades) omitted for simplicity. As shown in FIG. 4, assembly 10 includes upper bifurcation (bi-fi) fairing 40, lower bi-fi fairing 42, linkages 44 and 48 of first pivot door 22, linkages 46 and 50 of second pivot door 24, pivot axis 45 of first pivot door 22, pivot axis 47 of second pivot door 24, and actuator 52. Engine 18 is centered inside nacelle 12, in the illustrated embodiment, and thus is axially aligned with the engine fan at the front end of nacelle 12 (axis A of FIG. 1A). Upper bi-fi fairing 40 and lower bi-fi fairing 42 serve to interconnect nacelle 12 and engine 18, as well as provide additional stiffness for nacelle 12 and space for wires, tubes and other similar components. Linkage 44 provides a hinged connection between first pivot door 22 and pivot axis 45, with linkage 44 fixed to nacelle 12 at pivot axis 45. In the same manner, linkage 46 provides a hinged connection between second pivot door 24 and pivot axis 47, with linkage 46 fixed to nacelle 12 at pivot axis 47. Pivot axis 45 and pivot axis 47 can be positionally fixed relative to assembly 10, nacelle 12, and/or engine 18. Linkage 48 provides a connection between first pivot door 22 and actuator 52, while linkage 50 provides a connection between second pivot door 24 and actuator 52.

Actuator 52 pivots both first pivot door 22 and second pivot door 24 from the stowed position to the deployed position without translation of first pivot door 22, second pivot door 24, or any portion of nacelle 12. In the deployed position shown, first pivot door 22 and second pivot door 24 circumferentially surround inner surface 30 of bypass duct 26. First pivot door 22 and second pivot door 24 are configured to circumferentially surround inner surface 30 of bypass duct 26 such that an at least partially sealing mating relationship is formed and there is relatively little leakage of fan bypass stream F₁ (the only leakage coming from portions where bypass duct 26 is visible). This means that nearly all of fan bypass stream F₁ is redirected, resulting in a highly efficient pivot thrust reverser 20. Yet, at the same time entire pivot thrust reverser 20 can be deployed by a single actuator 52, and therefore, provides a simplified design requiring minimal parts, and thus increases reliability and reduces maintenance costs.

FIG. 5 is a perspective view of pivot thrust reverser 20 with a single actuator 52 in a deployed position. Certain assembly 10 components are left out for simplicity. Included, in addition to that shown and described previously, are motor 60, threaded rod 62, threaded knucklehead 64, cutouts 66 and 68, and aft edges 70 and 72. Actuator 52 is located between outer surface 28 of bypass duct 26 and outer surface 14 of nacelle 12 (see also FIG. 4). Actuator 52 can be, for example, a bolt screw linear actuator as shown here that includes motor 60, threaded rod 62, and threaded knucklehead 64. However, various other types of actuators can also be used in alternate embodiments to pivot both first pivot door 22 and second pivot door 24 between the stowed and deployed positions. Motor 60 moves threaded knucklehead 64 down threaded rod 62 towards motor 60, and in so doing, simultaneously pivots both first pivot door 22 and second pivot door 24 from the stowed position to the deployed position on fixed pivot axises 45 and 47 respectively. Linkages 44 and 46 are secured to nacelle 12 in the illustrated embodiment, and thus pivot axises 45 and 47 are fixed in place relative to nacelle 12. Pivot axis 45 is spaced from first pivot door 22 and extends linearly from linkage 44 to linkage 48. Similarly, pivot axis 47 is spaced from second pivot door 24 and extends linearly from linkage 46 to linkage 50. Because pivot axises 45 and 47 are fixed relative to nacelle 12, first pivot door 22 and second pivot door 24 are pivoted by actuator 52 between stowed and deployed positions without translating (relative to assembly 10).

Additionally, first pivot door 22 contains cutout 66 in aft edge 70 and second pivot door 24 contains cutout 68 in aft edge 72. Both cutouts 66 and 68 are located on lower portions of aft edges 70 and 72 respectively. When in the deployed position, as shown here, aft edge 70 of first pivot door 22 faces aft edge 72 of second pivot door 24. As a result, cutout 66 is aligned to face cutout 68 when pivot doors 22 and 24 are deployed, forming an opening in pivot thrust reverser 20 to accommodate engine 18. Both cutout 66 and cutout 68 can be arc-shaped, resulting in the opening in pivot thrust reverser 20 being generally circular in shape. However, in alternative embodiments, cutouts 66 and 68 can have various different shapes and be placed at any location on first pivot door 22 and second pivot door 24.

The present embodiments provide a highly effective thrust reverser 20 for use in a gas turbine engine. This is because configuring pivot doors 22 and 24 with cutouts 66 and 68 to surround a portion of inner surface 30 of bypass duct 26 as shown allows nearly all of fan bypass stream F₁ to be redirected in the appropriate direction, while at the same time minimizing the number of components needed to pivot both pivot doors 22 and 24 from the stowed to the deployed position. This is turn decreases the weight of thrust reverser 20 while increasing the reliability of thrust reverser 20. Additionally, the design of thrust reverser 20 provides a modular assembly which allows for direct mounting of thrust reverser 20 in position.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments of the present invention.

A pivot thrust reverser for use in a gas turbine engine assembly, the pivot thrust reverser comprising a first pivot door forming a first portion of an outer surface of a nacelle when stowed; a second pivot door spaced from the first pivot door forming a second portion of the outer surface of the nacelle when stowed, wherein the first pivot door and the second pivot door each form a portion of a surface of a bypass duct when in a stowed position, and wherein in the deployed position the first pivot door and the second pivot door circumferentially surround a portion of an inner surface of a bypass duct such that when the pivot thrust reverser is deployed during engine operation a fan bypass stream is redirected while both a core stream and a nacelle ventilation stream flow in substantially the same manner as when the pivot thrust reverser is stowed.

The pivot thrust reverser of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components:

An actuator configured to pivot both the first pivot door and the second pivot door from the stowed position to the deployed position, wherein the actuator is located between the surface of the bypass duct and the outer surface of the nacelle.

The actuator pivots both the first pivot door and the second pivot door from the stowed position to the deployed position on respective pivot axises that are each positionally fixed relative to the gas turbine engine assembly.

A first linkage on the first pivot door and a second linkage on the second pivot door where the first linkage on the first pivot door and the second linkage on the second pivot door both connect to the actuator.

The first linkage on the first pivot door and the second linkage on the second pivot door are both between the surface of the bypass duct and the outer surface of the nacelle.

The first pivot door and the second pivot door are axially aligned and radially opposite along an axis of the gas turbine engine assembly.

The second pivot door is spaced approximately 180° from the first pivot door relative to an axis of the gas turbine engine assembly.

A first cutout on the first pivot door.

A second cutout on the second pivot door.

Both the first cutout and the second cutout are each arc-shaped.

Both the first cutout and the second cutout are located at aft edges of the first pivot door and the second pivot door respectively.

When the first pivot door and the second pivot door are in the deployed position the aft edge of the first pivot door faces the aft edge of the second pivot door.

A method for reversing thrust of a gas turbine engine assembly, the method comprising providing a first pivot door, wherein the first pivot door forms both a portion of a surface of a bypass duct and a portion of an outer surface of a nacelle when in a stowed position; providing a second pivot door spaced from the first pivot door, wherein the second pivot door forms both a portion of the surface of the bypass duct and a portion of the outer surface of the nacelle when in the stowed position; pivotally deploying both the first pivot door and the second pivot door from the stowed position to a deployed position by an actuator, wherein the actuator is located between the surface of the bypass duct and the outer surface of the nacelle; circumferentially surrounding a portion an inner surface of a bypass duct with both the first pivot door and the second pivot door when the first pivot door and the second pivot door are in the deployed position; and redirecting a fan bypass stream during engine operation when the first pivot door and the second pivot door are in the deployed position.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, the following techniques, steps, features and/or configurations:

Both the first pivot door and the second pivot door are pivotally deployed by the actuator on respective pivot axises each positionally fixed relative to the gas turbine engine assembly.

A first pivot door with an aft edge; a second pivot door with an aft edge such that when the first pivot door and the second pivot door are in a deployed position the aft edge of the first pivot door and the aft edge of the second pivot door face each other; a first cutout on the first pivot door; and a linkage of the first pivot door and a linkage of the second pivot door each connected to an actuator which pivots the first pivot door and the second pivot door on pivot axises that are positionally fixed.

A second cutout on the second pivot door.

Both the first cutout and the second cutout are each arc-shaped.

The aft edge of the first pivot door and the aft edge of the second pivot each contain an arc-shaped cutout.

Any relative terms or terms of degree used herein, such as “substantially”, “essentially”, “generally” and the like, should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations, incidental alignment variations, temporary alignment or shape variations induced by operational conditions, and the like.

While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 

The invention claimed is:
 1. A pivot thrust reverser for use in a gas turbine engine assembly, the pivot thrust reverser comprising: a first pivot door forming a first portion of an outer surface of a nacelle when stowed; a second pivot door spaced from the first pivot door forming a second portion of the outer surface of the nacelle when stowed, wherein the first pivot door and the second pivot door are axially aligned and radially opposite along an axis of the gas turbine engine assembly and each form a portion of a surface of a bypass duct when stowed; an actuator configured to pivot both the first pivot door and the second pivot door from a stowed position to a deployed position; a first linkage on the first pivot door connected to the actuator; and a second linkage on the second pivot door connected to the actuator, wherein in the deployed position the first pivot door and the second pivot door circumferentially surround a portion of an inner surface of a bypass duct such that when the pivot thrust reverser is deployed during engine operation a fan bypass stream is redirected while both a core stream and a nacelle ventilation stream flow in substantially the same manner as when the pivot thrust reverser is stowed.
 2. The pivot thrust reverser of claim 1, wherein the actuator is located between the surface of the bypass duct and the outer surface of the nacelle.
 3. The pivot thrust reverser of claim 1, wherein the actuator pivots both the first pivot door and the second pivot door from the stowed position to the deployed position on respective pivot axes that are each positionally fixed relative to the gas turbine engine assembly.
 4. The pivot thrust reverser of claim 1, wherein the first linkage on the first pivot door and the second linkage on the second pivot door are both between the surface of the bypass duct and the outer surface of the nacelle.
 5. The pivot thrust reverser of claim 1, wherein the second pivot door is spaced approximately 180° from the first pivot door relative to the axis of the gas turbine engine assembly.
 6. The pivot thrust reverser of claim 1, further comprising a first cutout on the first pivot door.
 7. The pivot thrust reverser of claim 6, further comprising a second cutout on the second pivot door.
 8. The pivot thrust reverser of claim 7, wherein both the first cutout and the second cutout are each arc-shaped.
 9. The pivot thrust reverser of claim 8, wherein both the first cutout and the second cutout are located at aft edges of the first pivot door and the second pivot door respectively.
 10. The pivot thrust reverser of claim 9, wherein when the first pivot door and the second pivot door are in the deployed position the aft edge of the first pivot door faces the aft edge of the second pivot door.
 11. A method for use in a gas turbine engine assembly, the method comprising: providing a first pivot door, wherein the first pivot door forms both a portion of a surface of a bypass duct and a portion of an outer surface of a nacelle when in a stowed position; providing a second pivot door spaced from the first pivot door with the first pivot door and the second pivot door being axially aligned and radially opposite along an axis of gas turbine engine assembly, wherein the second pivot door forms both a portion of the surface of the bypass duct and a portion of the outer surface of the nacelle when in the stowed position; pivotally deploying both the first pivot door and the second pivot door from the stowed position to a deployed position by an actuator, a first linkage connecting the first pivot door to the actuator, and a second linkage connecting the second pivot door to the actuator; circumferentially surrounding a portion of an inner surface of a bypass duct with both the first pivot door and the second pivot door when the first pivot door and the second pivot door are in the deployed position; and redirecting a fan bypass stream during engine operation when the first pivot door and the second pivot door are in the deployed position.
 12. The method of claim 11, wherein both the first pivot door and the second pivot door are pivotally deployed by the actuator on respective pivot axes each positionally fixed relative to the gas turbine engine assembly.
 13. A pivot thrust reverser for use in a gas turbine engine assembly, the pivot thrust reverser comprising: a first pivot door forming a first portion of an outer surface of a nacelle when stowed, the first pivot door including a first cutout; a second pivot door spaced from the first pivot door forming a second portion of the outer surface of the nacelle when stowed, wherein the pivot doors each form a portion of a surface of a bypass duct when stowed; an actuator configured to pivot both the first pivot door and the second pivot door from a stowed position to a deployed position; a first linkage on the first pivot door connected to the actuator; and a second linkage on the second pivot door connected to the actuator, wherein in the deployed position the first pivot door and the second pivot door circumferentially surround a portion of an inner surface of a bypass duct such that when the pivot thrust reverser is deployed during engine operation a fan bypass stream is redirected while both a core stream and a nacelle ventilation stream flow in substantially the same manner as when the pivot thrust reverser is stowed.
 14. The pivot thrust reverser of claim 13, further comprising a second cutout on the second pivot door.
 15. The pivot thrust reverser of claim 14, wherein both the first cutout and the second cutout are each arc-shaped.
 16. The pivot thrust reverser of claim 15, wherein both the first cutout and the second cutout are located at aft edges of the first pivot door and the second pivot door respectively.
 17. The pivot thrust reverser of claim 16, wherein when the first pivot door and the second pivot door are in the deployed position the aft edge of the first pivot door faces the aft edge of the second pivot door. 